Transverse ligament:
Can simulate grade 3 oblique tears, in up to 30% of MR examinations, adjacent to anterior horn of LM on sagittal images and is created by fat between anterior horn and transverse ligament.
Infrequently, can mimic MM tearRemember isolated anterior horn tears are uncommon
Central rhombdoid attachment of anterior horn of the lateral meniscus:
May itself show increased signal.
On sagittal directed obliquely upwards and may be seen on more than 1 image adjacent to intercondylar notch
Branch from lateral inferior geniculate artery:
May mimic tear adjacent to anterior horn of LM
Meniscofemoral ligament:
Meniscal insertion may micmic vertical tear in the posterior horn of LM due to fat between LM and MFL
Popliteus tendon sheath:
Mimics grade 3 tear in the posterior horn of LM
Intermediate on T1 and T2Runs oblique from front to back in superior to inferior direction
Usually tears are oriented opposite to that of popliteus tendon, but vertical tear may be parallel.
Pseudo bucket-handle tear:
In coronal MRI, when knee in external rotation, body and posterior horn of LM seen in same section mimics bicket handle tear
Correlation with sagittal images is needed
Lax meniscal sign (buckled meniscus):
Commonly seen in MM. Often secondary to fractures and joint laxity. May simulate tear
Vacuum phenomenon:
Produces blooming artefact on GRE
Pseuo loose body:
Intercondylar notch signal on T2* or fat-sat images. T1 will solve the dilemmaMCL bursa:Seen between MM and MCL and bursa may be mistaken for tear
Fibrillation:
High signal restricted to the apex without foreshortening or abnormal morphology
Diffuse meniscal edema:
Rarely seen similar to fibrillation, but more prominent
Magic angle effect:
Seen in medial segment of posterior horn of LM
Partial volume averaging:
Seen in the periphery
More common in MM 30%, LM 6%
